Shale shaker is the first stage equipment in a complete set of solids control system to separate coarse solids out of the spent drilling fluids, then the liquids will be transported to 2nd and 3rd stage equipment to further separate the fine solids out from the drilling fluids. So in a solids control system, the desander and desilter cyclones are the 2nd and 3rd stage equipment. The working principles of both desander and desilter are same, the diffidence is the size of cyclones.

Imagine what will happen if a tornado inside of a bottle, then you will get a simple and general idea on how a cyclone works.

When the drilling fluids is injected into a cyclone with high speed in the tangential direction, the drilling fluids will spiral like a tornado downward and gravitate towards the cyclone wall because of the centrifugal force and inertia. The larger the solids are, the more preferentially the solids will settle. As the cyclones narrows, the drilling fluids at the innermost and center of the cyclone will spiral towards the overflowing port thus a low pressure area inside the cyclone where the clean air goes through the underflow port. While the solids with large mass can not turn back to the overflow port because of their momentum but continue spiral downwards and come out from the underflow port. Therefore the clean fluids will flow out through the overflow port, and solids will be discharged from the drilling fluids.

GN desander is composed with10’’ cyclones made from PU for a longer service since this material is much more anti-abrasive than cast iron; GN desilter is composed with 4’’ cyclones also made from PU. The large the cyclones are, the larger the treating capacity will be.